Replacing secondary heat exchanger.

[robertoi]

My boiler is playing up, and the root cause of the problem seems to be the secondary heat exchanger being full of gunk. British gas home care wont cover it as its a corrosion/ scale problem...

In the service manual, it looks pretty easy to remove and repalce - so just wanted to check that there is nothing in law to stop me doing this myself is there?

Cheers

 

[nickso]

no, which boiler?

 

[robertoi]

An ariston microgenus - piece of crap I know but a new one is out of the question!

 

[petit_pablo]

An ariston microgenus - piece of rubbish I know but a new one is out of the question!

Easy to do, 2 screws holds it in.

If BG have already advised you of the sludge problem then they can still change it on a chargeable job, i charge customers a standard labour price on these jobs. Comes out at £108ish in oxford but the price varies depending on location.

If BG havent previously advised you of sludge problems then they should replace it FOC and advise any further work caused by sludge would be chargeable

 

[robertoi]

Well.....they've been out about 5 times now, first of all replaced pump, then diverter valve, and at time said heat exchanger had some muck in it, but that they had got some/ most of it out. THey then had to come back as a something was leaking, and water temp was nowhere near high enough. At this stage they said 'could be the thermister, or could be the heat exchanger - we'll change them both'. When they came today I was expecting the thermister and the heat exchanger to be replaced, only to be told they were only replacing the thermister because home care doesnt cover sludge problems.

THey never mentioned sludge problem at first visit (only ~2.5 months ago), and never told me I should get it sorted myself outside of homecare agreement, before today. THey also said that my job was a 'monitored job' cos of number of times they'd been out - although at least 2 of those visits were because they'd rushed the previous visist so much they'd not done something correctly (at one stage they went away without reconnecting a thermister cable to the diverter valve so water was superheating at that point.....)...

Reckon I should insist on them doing it for free? THey said it'd cost £120.

 

[petit_pablo]

Reckon I should insist on them doing it for free? THey said it'd cost £120.

Read the terms and conditions about sludge issues. If BG havent advised you of sludge problems and the need to flush etc before this problem then they should be doing FOC and advising you to get dirty system sorted.

 

[nickso]

Reckon I should insist on them doing it for free? THey said it'd cost £120.

Read the terms and conditions about sludge issues. If BG havent advised you of sludge problems and the need to flush etc before this problem then they should be doing FOC and advising you to get dirty system sorted.

agreed. and the monitored job thing is just a new trial they are doing, at the moment it means nothing.

 

[robertoi]

sorry - being a bit thick - does 'doing it FOC' mean they should be doing it for free?

 

[BigBurner]

An ariston microgenus - piece of rubbish I know but a new one is out of the question!

Easy to do, 2 screws holds it in.

Make sure you get new seals for it. Fit a Magnaclean, Spirovent or Sentinel filter (which looks like a rebadged Spirovent) on the CH return pipe. After cleaning with Fernox, flushing and filling with inhibitor of course.

Use Fermox DS3, available from B&Q, to descale the Heat Exchanger.

The non-condensing Microgenus is decent little combi, although a bit noisy. Quite reliable. Keep the system clean and it should give good service.

 

[BigBurner]

My boiler is playing up, and the root cause of the problem seems to be the secondary heat exchanger being full of gunk.

Is the gunk on the fresh water side? Scale? The water drops when scaled up. On the primary side sludge would block it, which means cleaning it and taking measures to clean the system and prevent it happening again.

 

[robertoi]

Thanks for all the suggestions.

Last night I flushed it out (not with powerflush) 5 times and water was still brown after that, with suspended chunks of iron oxide. Decided not worth flushing that way again for now - so just chucked in inhibitor and some descaling treatment for now.

My plan is to do powerflush myself (not paying BG £700 to do it....), then fit a magnaclean, and then get a replacement heat exchanger fitted.

Ive read that its not such a great idea to use acidic descaling/ powerflush treatments in boiers with aluminium heat exchangers - is there any truth in this? THere arent that many non acidic chems on the market from what I can see, and surely its only in there for a few hours, so it cant do that much damage.

Any chance someone could give me the part number for the exchanger? To fit I just need to totally drain both the CH circuit and the DHW right?

Cheers

 

[Rico99]

Hi there,

You are correct, YOU cannot use scidic cleansing solution on any aluminium components.

You need to get some Kamco Hyperflush, just as strong but NON acidic.

Rico

 

[robertoi]

THanks - how about inhibiting/ anti scale solutions which have acid compounds in them - eg the No Nonsense anti boiler noise stuff? Surely thats pretty weak acid isnt it? Ive got some of their anti noise and inhibitor in at the moment and the pH of the CH water is alkali rather than neutral.